[fuchsia] Add ScopedFxLogger

Also add a function for creating an fx_logger from a LogSink.
These will be used in subsequent CLs.

Bug: 1136681,1088094
Change-Id: I9e4fe1b2b0640fa3f7eb9e0891ae9ef1a80b8bcf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2530259
Auto-Submit: David Dorwin <ddorwin@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826204}

base/BUILD.gn

@@ -1564,6 +1564,8 @@ component("base") {
       "fuchsia/intl_profile_watcher.h",
       "fuchsia/process_context.cc",
       "fuchsia/process_context.h",
+      "fuchsia/scoped_fx_logger.cc",
+      "fuchsia/scoped_fx_logger.h",
       "fuchsia/scoped_service_binding.h",
       "fuchsia/scoped_service_publisher.h",
       "fuchsia/service_provider_impl.cc",
@@ -1619,10 +1621,12 @@ component("base") {
     public_deps += [
       "//third_party/fuchsia-sdk/sdk/fidl/fuchsia.intl",
       "//third_party/fuchsia-sdk/sdk/fidl/fuchsia.io",
+      "//third_party/fuchsia-sdk/sdk/fidl/fuchsia.logger",
       "//third_party/fuchsia-sdk/sdk/pkg/async",
       "//third_party/fuchsia-sdk/sdk/pkg/fdio",
       "//third_party/fuchsia-sdk/sdk/pkg/fidl_cpp",
       "//third_party/fuchsia-sdk/sdk/pkg/sys_cpp",
+      "//third_party/fuchsia-sdk/sdk/pkg/syslog",
       "//third_party/fuchsia-sdk/sdk/pkg/vfs_cpp",
       "//third_party/fuchsia-sdk/sdk/pkg/zx",
     ]

base/fuchsia/scoped_fx_logger.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/fuchsia/scoped_fx_logger.h"
+
+#include "base/fuchsia/fuchsia_logging.h"
+
+namespace base {
+
+ScopedFxLogger CreateFxLoggerFromLogSink(
+    fuchsia::logger::LogSinkHandle log_sink) {
+  // TODO(bugs.fuchsia.dev/63529): Use |log_sink_socket| when available.
+  zx::socket client_end, request_end;
+  zx_status_t status =
+      zx::socket::create(ZX_SOCKET_DATAGRAM, &client_end, &request_end);
+  if (status != ZX_OK) {
+    return nullptr;
+  }
+  fuchsia::logger::LogSinkSyncPtr log_sink_ptr;
+  log_sink_ptr.Bind(std::move(log_sink));
+  log_sink_ptr->Connect(std::move(request_end));
+
+  fx_logger_config_t config = {
+      // Selecting based on log level is handled outside the fx_logger.
+      .min_severity = FX_LOG_ALL,
+      .console_fd = -1,
+      .log_service_channel = client_end.release(),
+      // Do not set any custom tags.
+      .tags = nullptr,
+      .num_tags = 0,
+  };
+
+  fx_logger_t* fx_logger = nullptr;
+  status = fx_logger_create(&config, &fx_logger);
+  if (status != ZX_OK) {
+    ZX_LOG(ERROR, status) << "fx_logger_create";
+    return nullptr;
+  }
+
+  return ScopedFxLogger(fx_logger);
+}
+
+}  // namespace base

base/fuchsia/scoped_fx_logger.h

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_FUCHSIA_SCOPED_FX_LOGGER_H_
+#define BASE_FUCHSIA_SCOPED_FX_LOGGER_H_
+
+#include <fuchsia/logger/cpp/fidl.h>
+#include <lib/syslog/logger.h>
+
+#include <memory>
+
+#include "base/base_export.h"
+
+namespace base {
+
+namespace internal {
+
+struct FxLoggerDeleter {
+  inline void operator()(fx_logger_t* ptr) const { fx_logger_destroy(ptr); }
+};
+
+}  // namespace internal
+
+using ScopedFxLogger = std::unique_ptr<fx_logger_t, internal::FxLoggerDeleter>;
+
+// Creates a new logger connected to the specified |log_sink| service.
+// The logger is configured to log all severities of message, and has no
+// custom tags set.
+// Returns null if creation of the new logger fails.
+BASE_EXPORT ScopedFxLogger
+CreateFxLoggerFromLogSink(fuchsia::logger::LogSinkHandle log_sink);
+
+}  // namespace base
+
+#endif  // BASE_FUCHSIA_SCOPED_FX_LOGGER_H_